Please note: This has no relation to any real persons on this site or elsewhere and should not be taken to be such.
In my world there is a human nomadic desert tribe. They have a long-standing custom of refraining from defecating on their journeys. They wait until they reach an oasis.
This is important to the structure of my world but I need a reason for them to do this. Can anyone help?
P.S. There is no religious element to this behaviour - it has to be for a practical reason.
I use the term anal retentive because the tribe have trained themselves to retain fecal matter in their anuses in addition to the rectum as is normal. This allows the storage of a larger volume. In my 'alternate history' (see tag), the phrase was stolen by Freud when he made a reference to this tribe.